The invention relates to a method for monitoring the transport of a thread, in particular the insertion of a weft thread in a weaving machine, and to a weaving machine which is equipped for carrying out a method of this kind.
Within the framework of general process optimization and automation in textile technology the measurement and monitoring of the instantaneous dynamic process parameters which are characteristic for the thread transport are given great importance. In the following, dynamic process parameters will be understood to mean principally parameters which effect a movement of the thread, i.e. forces which act on the thread. For example, in current weaving machines, the warp thread tensions are measured and used for regulation of the warp thread let-off drive. In contrast, in current weaving machines the measurement of the thread tensile forces which act on a weft thread takes place mostly only within the framework of experimental projects. This restriction can largely be attributed to the fact that the thread must be deflected for the measurement of the thread tensile force in order to produce a normal force which acts on the measurement cell. If a deflection is not already present which can be utilized, then an additional deflection is required, which can severely hinder the thread transport depending on the deflection angle. This holds in particular for weaving machines with air insertion systems. Analogously to this, there is a large number of situations in textile machines in which the direct measurement of the desired dynamic process parameters which are characteristic for the thread transport presents difficulties or is associated with greater cost and complexity. This holds, e.g., for measurements over longer transport sections or at points which are difficult to access, or for the measurement of thread tensile forces which arise in the thread transport that could not be previously carried out without contact.